The human eye in its simplest terms functions to provide vision by transmitting and refracting light through a clear outer portion called the cornea, and further focusing the image by way of the lens onto the retina at the back of the eye. The quality of the focused image depends on many factors including the size, shape and length of the eye, and the shape and transparency of the cornea and lens. When trauma, age or disease cause the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. The treatment for this condition is surgical removal of the lens and implantation of an artificial lens or IOL.
While early IOLs were made from hard plastic, such as polymethylmethacrylate (PMMA), soft, foldable IOLs made from silicone, soft acrylics and hydrogels have become increasingly popular because of the ability to fold or roll these soft lenses and insert them through a smaller incision. Several methods of rolling or folding the lenses are used. One popular method is an injector cartridge that folds the lenses and provides a relatively small diameter lumen through which the lens may be pushed into the eye, usually by a soft tip plunger, such as the one described in U.S. Pat. No. 4,681,102 (Bartell), which includes a split, longitudinally hinged cartridge. Similar designs are illustrated in U.S. Pat. Nos. 5,494,484 and 5,499,987 (Feingold) and 5,616,148 and 5,620,450 (Eagles, et al.). Other cartridge designs include, for example, U.S. Pat. Nos. 5,275,604 (Rheinish, et al.) and 5,653,715 (Reich, et al.).
It is desirable for any combination of cartridge and handpiece used in an intraocular lens delivery system to be comfortable and intuitive for the surgeon to use. An intraocular lens delivery system with a good “feel” for the surgeon can improve the ease and success rate of surgical procedures in which the intraocular lens delivery system is employed.